Amgen (AMGN) S-4 Registration of securities issued in business combination transactions

EXHIBIT 23.1

CONSENT OF ERNST & YOUNG LLP, INDEPENDENT AUDITORS

We consent to the reference to our firm under the caption “Experts” in the Registration Statement (Form S-4) to be filed on April 26, 2004, and related Prospectus of Amgen Inc. for the registration of its common stock and to the incorporation by reference therein of our report dated January 21, 2004, with respect to the consolidated financial statements and schedule of Amgen Inc. included in this Annual Report (Form 10-K) for the year ended December 31, 2003, filed with the Securities and Exchange Commission.

/s/    ERNST & YOUNG LLP

Los Angeles, California

April 22, 2004